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<body>
  
  <script>

    const names = ["abc", "cba", "nba"]
    
    // 给数组names创建一个迭代器(迭代器: names的跌大气)
    let index = 0
    const namesIterator = {
      next: function() {
        // done: Boolean
        // value: 具体值/undefined
        if (index < names.length) {
          return { done: false, value: names[index++] }
        } else {
          return { done: true }
        }
      }
    }

    console.log(namesIterator.next())
    console.log(namesIterator.next())
    console.log(namesIterator.next())
    console.log(namesIterator.next())

    // 数组nums
    const nums = [100, 24, 55, 66, 86]
    
    let indexNum = 0
    const numsIterator = {
      next: function() {
        // done: Boolean
        // value: 具体值/undefined
        if (indexNum < nums.length) {
          return { done: false, value: nums[indexNum++] }
        } else {
          return { done: true }
        }
      }
    }

  </script>

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